1. Field of the Invention
The present invention relates to a ball screw unit with dust cleaning and ball deflecting element fixing mechanism, more particularly, to a mechanism for dust cleaning and ball deflecting element fixing which has a specially designed and structurally simple dust scraper to clean the dust along the ball screw unit and at the same time, forcibly hold the ball deflecting element at position.
2. Description of the Prior Art
The ball screw unit is well-known for its excellent mobility with mechanical precisement, suitable for serving precision industry such as for fabrication of mounting of a finishing tool thereby trending towards miniaturization and simplification in its structure. The conventional ball screw unit is essentially composed of a ball screw and a nut proper coupled with it. Each of two ends of the nut proper is provided with a ball deflecting element for circulating balls to roll in and out the ball screw unit. The ball deflecting ingress of dust, rubbishes and trashes into the nut proper, a scraper is usually equipped at one side of the ball deflecting element to perform cleaning work. It is therefore a conventional ball screw unit is deemed to have a complicated structure including lots of component parts resulting in increasing difficulty in fabrication, assembly and thus raising production cost.
As shown in FIG. 1 and FIG. 2 (a recent patented case), the essential feature of the nut proper 6 has a rolling spiral slot 61 formed on the inner wall of the nut proper 6, and a circulation tunnel 62 is formed at each end of the rolling spiral slot 61 for leading to the ball deflecting element 65. It is characterized by having an annular inlaid slot 63 at each end of the nut proper 6 facing against the outside of the ball deflecting element 65, and a C shaped annular packing 7 is clogged in the annular inlaid slot 63, furthermore, the contact surface between the inner wall of the annular inlaid slot 63 and outer wall of the C shaped annular packing 7 are chamfered to form a sloped surface 64 and 71 respectively (see FIG. 2) such that the C shaped annular packing 7 clogs tightly in the annular inlaid slot 63 and forcibly hold the ball deflecting element 65.
Meanwhile, the structure shown in FIG. 2 is problematic. The C shaped annular packing can not perfectly impose on the ball deflecting element 65 should material used be improper and the mechanical finishing unqualified so as to leave a gap 72 therebetween thereby causing the ball deflecting element 65 to vibrate during the operation of the ball screw unit. Besides, the afore said chamfered surfaces 64 and 71 on the annular inlaid slot 63 and the C shaped packing 7 are uneasy to form, and it is hard to stably hold the ball deflecting element 65 at position without the chamfered surfaces 64 and 71. Should there is no sufficient fabrication technique, there is no way to manufacture such a strictly precise mechanical product.
In addition, the above described structure is only aimed at fixing the ball deflecting element 65, it has not yet considered equipping dust clearing means between two sides of the nut proper 6 and the corresponding ball screw. The entire structure is unable to work perfectly unless it is constructed more complicated.
For these defects noticeable on the prior arts, an improvement is seriously required.
The inventor of the present invention has put forth every effort for years by continuous research and experimentation attempting to find out the remedy to palliate the inherent shortcomings of the conventional techniques described above, and at last has succeeded in coming out with the present invention.